Paper feeder



Feb. 13, 1968 C. o SUTTON 3,368,727

PAPER FEEDER Filed March 16, 1966 alBYMk/g l TTONEYS United States Patent O 3,368,727 PAPER FEEDER Charles 0. Sutton, San Francisco, Calif., assignor to The American Binder Company of California, a corporation of California Filed Mar. 16, 1966, Ser. No. 534,882 4 Claims. (Cl. 226-74) This invention relates to a paper-propelling device, and more specifically relates to the type of paper-propelling device known as a tractor.

Continuous business forms ordinarily have a series of perforations on each side so that they can be propelled through various machines by the use of sprockets or tractors. A tractor unit consists of a short run of endless chain having a series of pins thereon and is generally preferred to the use of a sprocket since a large number of pins are in contact with the perforations at any one time. Thus the papers can be propelled through the machine at a high rate of speed without danger of tearing out the sprocket holes. One difficulty which exists with the tractor drive is that at the end of the straight run of the chain, the chain passes over a driving sprocket, causing the associated pins to tilt in a forward direction, tending to engage the sprocket holes and pull the paper down and possibly tear it.

One suggested solution to this problem is to provide a series of trailing tabs extending from each of the driving pins to the vicinity of the next adjacent pin to the rear. In such a tractor assembly, as one pin starts its downward path of travel around the end driving sprocket, the trailing portion of the tab raises the paper off of the next adjacent pin, thus preventing any tendency of the pin to tear out the perforation. However, this scheme is not suitable in a number of operations wherein the paper must be kept flat while some other operation is performed, such as printing or edge trimming.

According to the present invention, a superior tractor is provided wherein there is no tendency for the descending pins at the end of a run of chain to tear out the perforations. Further, in accordance with the present invention, an improved form of tractor is provided wherein the paper is not lifted off of the pins but instead remains level as it leaves the tractor unit.

A further advantage of the present invention is that a superior form of tab is provided for holding the pins, wherein one tab supports the next adjacent tab as the tabs go over a sprocket.

A still further advantage of the invention is the provision of a novel pin shape which has no tendency to wedge in a perforation in the paper.

In the drawings forming part of this application:

FIGURE 1 is a top-plan view of one side of a tractor unit embodying the present invention.

FIGURE 2 is a side view on the line 2 2 of FIG- URE 1.

FIGURE 3 is an enlarged perspective view of a portion of a drive chain with the associated tab and pin assembly.

FIGURE 4 is a side view in section showing the manner in which the tabs hold the paper level as the end pin descends around a sprocket.

FIGURE 5 is a diagrammatic view of a prior art structure showing the tendency of the pin to engage and tear the paper.

Turning now to the description of the drawings by reference characters, the device of the present invention includes a driving sprocket 7 and an idler sprocket 9 with an endless chain 11 trained around the sprockets to provide an upper straight run generally designated 13. A bed plate 14 supports the perforated paper 16. Each pair of links has a tab 1S extending therefrom carrying a pin 17. Each tab 15 has a trailing edge 18 and a leading arm 3,368,727 Patented Feb. 13, 1968 ice 19 which extends forward over the next adjacent tab, the ahm 19 having an offset forming a knee 21, so that the arm 19 will lie over and be parallel with the next adjacent tab. Obviously, the offset should be about the thickness of the tab. Arm 19 can be made in Various forms, but preferably has a notch 23, at one end thereof which partially surrounds the pin on the next adjacent tab as is best seen in FIGURE 3.

In FIGURE 4 the exact method of operation of the present invention is shown. Here a series of accounting forms generally designated 25 and consisting of three thicknesses of paper, although a greater or a smaller number of sheets might be employed, have mating sprocket holes, 27. The forms are being conveyed through a machine, and it will be noted that the pins 17A and 17B are engaged in sprocket holes and are actively driving the papers forward, It will also be seen that the arm 19B is supporting the papers in a horizontal fashion, and pin 15C is descending at an angle and thus being withdrawn from a sprocket hole. It can thus be seen that positive support is given to the papers while the pin is being withdrawn, obviating any tendency of the descending pin to tear out the sprocket holes. Further, the paper is kept flat and parallel to the plane of the bed. This should be contrasted with the prior art showing of FIGURE 5. Here the pin 29 is descending while it is still engaged with the papers 31. It will be noted that the pin is tilted in a forward direction, tending to wedge in the sprocket hole and pull the paper down, thus tending to tear out the sprocket hole.

Of necessity, the tabs holding the pins must be made of thin metal and are subject to a substantial strain, particularly at the point where they pass over a sprocket. An important aspect of the present invention is that one tab supports the next adjacent tab at the end of a horizontal run. Referring again to FIGURE 4 it will be seen that the trailing edge 18C ts into the knee 21B, thus lending support to the next tab 15B to the rear. Further, it will be been in FIGURE 4 that the pins have a curved configuration to avoid binding and that if one strikes an arc having as its center the forward base of pin 17B and having as its diameter the center to center distance of pins 17B and 17C, all of pin 17C will lie within the arc. Thus as the pin turns the corner, it does not tend to bind in the perforation.

Although the arm 19 is shown as partially surrounding the next adjacent pin with a notch 23, therein, it is obvious that the spirit of this invention could be carried out with other configurations of the arm. Thus, the arm might completely surround the pin and have a hole therein to accommodate the next adjacent pin, or it might merely lie one side or the other of the pin.

It is apparent from the foregoing that I have provided a simple yet effective tractor mechanism wherein there is no tendency for the pin at the end of the run to tear out the sprocket holes, yet the papers being conveyed are maintained in a horizontal plane as they leave the tractor and are thus neither lowered nor raised at the end of the run.

I claim:

1. A tractor form feed for propelling a sheet having perforations at the edge thereof, comprising in combination:

(a) an endless chain having a plurality of links;

(b) said chain having a straight run and passing over a sprocket at the end of said straight run;

(c) tabs extending from at least some of said links,

each of said tabs having a pin thereon;

(d) each of said pins being in mating relationship with one of said perforations;

(e) an arm extending forward in the direction of travel from each of said tabs;

3 4 (f) each of said arms terminating adjacent to the next 4. The structure of claim 1 wherein the pins have an forward pin whereby; arcuate shape and wherein the diameter of the arc is sub- (g) said arm supports said sheet at the end of the stantiaiiy the distance between like points on adjacent straight run as said chain passes over the sprocket. pins. 2. The structure 0f claim 1 wherein said arm is notched 5 References Cited with the notch partly surrounding the next adjacent pin.

3. The structure of claim l wherein the arm is offset UNITED STATES PATENTS upwardly from the tab by about the thickness of the tab, 3,015,425 1 1962 Wicklund 226-74 thereby forming a knee and wherein the trailing edge of 3,209,973 10/1965 Eichom 226-74 one tab contacts the knee of the next trailing tab when 10 the chain passes over the sprocket at the end of the ALLEN N. KNOWLES, Primary Examiner.

straight run, thereby supporting the sanne. 

1. A TRACTOR FORM FEED FOR PROPELLING A SHEET HAVING PERFORATIONS AT THE EDGE THEREOF, COMPRISING IN COMBINATION: (A) AN ENDLESS CHAIN HAVING A PLURALITY OF LINKS; (B) SAID CHAIN HAVING A STRAIGHT RUN AND PASSING OVER A SPROCKET AT THE END OF SAID STRAIGHT RUN; (C) TABS EXTENDING FROM AT LEAST SOME OF SAID LINKS, EACH OF SAID TABS HAVING A PIN THEREON; (D) EACH OF SAID PIN BEING IN MATING RELATIONSHIP WITH ONE OF SAID PERFORATIONS; 